This invention relates to articles with a multi-layer decorative and protective coating thereon.
It is currently the practice with various articles, particularly brass articles such as faucets, faucet escutcheons, door knobs, door handles, door escutcheons and the like, to first buff and polish the surface of the article to a high gloss and then apply a protective organic coating, such as one comprised of acrylics, urethanes, epoxies, and the like, onto this polished surface. This system has the drawback that the buffing and polishing operation, particularly if the article is of a complex shape, is labor intensive. Also, the known organic coatings are not always as durable as desired, and are susceptible to attack by chemicals such as acids. It would, therefore, be quite advantageous if brass articles, or indeed other articles, either plastic, ceramic, or metallic, could be provided with a coating which gave the article the appearance of highly polished brass, provided wear resistance and corrosion protection, and also provided improved chemical, such as acid, resistance. The present invention provides such a coating.
The present invention is directed to an article such as a plastic, ceramic, or metallic, particularly a metallic article, having a multi-layer coating deposited on at least a portion of its surface. More particularly, it is directed to an article, particularly a metallic article such as stainless steel, aluminum, brass or zinc, having deposited on its surface multiple superposed layers of certain specific types of materials. The coating is decorative and also provides corrosion resistance, wear resistance and improved chemical resistance such as improved resistance to acids and bases. In one embodiment the coating provides the appearance of highly polished brass, i.e. has a brass color tone, while in another embodiment it provides a chrome color.
The article has deposited on its surface a polymeric base coat layer. The polymeric base coat layer functions to level the surface of the article, cover any scratches or imperfections in the surface of the article, and provide a smooth and even surface for the deposition of the subsequent layers of the multi-layered coating.
In one embodiment deposited over the polymeric base coat layer is an adhesion promoting layer comprised of chromium. Over the adhesion promoting chromium layer is deposited a relatively thick strengthening layer comprised of chromium compound. Over the chromium compound strengthening layer is a sandwich layer comprising a multiplicity of alternating layers of a refractory metal compound or refractory metal alloy compound and a refractory metal or refractory metal alloy. Over the sandwich layer is a color layer comprising a metal or metal alloy such as chromium or stainless steel, or a reacted metal compound such as zirconium nitride or titanium-zirconium carbonitride. In one embodiment over the color layer is a transparent protective metal compound layer.
In another embodiment the adhesion promoting chromium layer is absent and the chromium compound strengthening layer is deposited directly onto the polymeric base coat layer.
All metal and reacted metal compound layers are deposited by a vapor deposition method such as physical vapor deposition including cathodic arc evaporation and sputtering.